Document feeding apparatus

ABSTRACT

A document feeding apparatus includes a driven roller and a feed roller rotatable with a drive shaft, an idle roller gearing with the driven roller and a document feeder. The document feeder includes a pick-up roller having a shaft portion, a cam slipping into the shaft portion and a driven gear gearing with the idle roller, a protrusion disposed on the shaft portion, one end of the cam being a spiral shape defining an end thereof, and another end defining a first engaging portion and a second engaging portion thereof, a lump disposed at a lateral of the driven gear. The feeding apparatus keeps in separation of the document from a next feed-in document and prevents the documents from overlapping.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a document feeding apparatus used in an office machine, and more specifically relates to a document feeding apparatus having a simple mechanism.

2. The Related Art

Generally, a document feeding apparatus is used in an office machine, a such as a fax machine, a scanner, a printer, a copy machine, or a multi-function peripheral (MFP), to convey the document into the office machine.

In the conventional machine, the document feeder uses the paper-stopping plate to align the lead edge of the document to make sure accurate orientation of the document. Afterwards, the pick-up roller feeds in the document one by one to avoid conveying two or more documents at the same time. Such mechanism is named ADF, Automatic Document Feeder. The ADF is better to have good performances on paper alignment and conveyance in order to avoid the double feeding and jamming problems.

However, in a conventional ADF, an electromagnetic valve is utilized to coordinate the operation between the pick-up roller and the paper-stopping plate. The drawback of the conventional approach is high cost and require more complex mechanism to achieve a better performance on feeding papers accurately. Therefore, it is desired to provide a document feeding apparatus of simple mechanism and low cost.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a document feeding apparatus that is used in an office machine, such as a fax machine, a scanner, a printer, a copy machine, or a multi-function peripheral (MFP).

Another object of the present invention is to provide a document feeding apparatus that conveys document one by one without concerns of overlapping feeding document.

Another object of the present invention is to provide a document feeding apparatus that has a simple mechanism. The approach is low cost.

The present invention includes a driven roller and a feed roller rotatable with a drive shaft, an idle roller gearing with the driven roller and a document feeder. The document feeder includes a pick-up roller having a shaft portion, a cam slipping into the shaft portion and a driven gear gearing with the idle roller, a protrusion disposed on the shaft portion, one end of the cam being a spiral shape defining an end thereof, and another end defining a first engaging portion and a second engaging portion thereof, a lump disposed at a lateral of the driven gear.

Other objects, novel features and advantages of the present invention will become more apparent from the following detailed description of a preferred embodiment thereof when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a document feeding apparatus in accordance with the present invention;

FIG. 2 is an exploded perspective view of a document feeder of the document feeding apparatus;

FIG. 3 is a perspective view showing a lump of a driven gear rotates to touch the first engaging portion of a cam;

FIG. 4 is a sectional view showing the document feeder is rotated to convey the document;

FIG. 5 is a sectional elevation view showing the document transfers a power from a driven roller to rotate with a pick-up roller;

FIG. 6 is a perspective view showing the lump of the driven gear moves to and touches the second engaging portion of the cam; and

FIG. 7 is a sectional view showing the document leaves the pick-up roller, and the pick-up roller stops rotating.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In order to illustrate the present invention particularly, including technology, structure traits, aims and efficiency, a detailed explanation of a preferred embodiment of the present invention will be given thereinafter, with reference to the annexed drawings, for better understanding thereof to those skilled in the art.

Referring to FIG. 1, the document feeding apparatus 100 of the present invention includes a driven roller 20 and a feed roller 50 fixed to and rotatable with a drive shaft 10, a document feeder 30 and an idle roller 40 gearing the driven roller 20 and the document feeder 30. The driven roller 20, the document feeder 30 and the idle roller 40 gear each other.

Please further refer to FIG. 2, the document feeder 30 includes a pick-up roller 31 having a shaft portion 311 extending from a lateral of the pick-up roller 31, a cam 32 slipping into the shaft portion 311 and a driven gear 33 gearing with the idle roller 40 fixed to the shaft portion 311. A protrusion 312 is disposed on the shaft portion 311 and adjoins to the lateral of the pick-up roller 31. One end of the cam 32 is a spiral shape 324 defining an end 321 thereof, and the other end is a hollow shape defining a first engaging portion 322 and a second engaging portion 323 thereof. A plane is disposed therebetween and connects the first engaging portion 322 and the second engaging portion 323. The plane stretches from the first engaging portion 322 to the second portion 323 for forming an inclined plane 325. A lump 331 is disposed at a lateral of the driven gear 33 and extending forwardly.

To assemble the document feeder 30, the cam 32 passes through the shaft portion 311. The driven gear 33 is fastened to the end of the shaft portion 311, so that the cam 32 could be rotated between the shaft portion 311 and the driven gear 33.

The motion of the document feeder 30 is as followings. Referring to FIGS. 1 and 3, the driving device (not shown, such as a step motor) provides the drive shaft 10 a power to rotate, and then the driven roller 10 and the feed roller 50 are rotated at the same time. Since the idle roller 40 is geared with the driven roller 20 and the driven gear 33, the driven gear 33 is rotated simultaneously. The lump 331 of the driven gear 33 rotates to touch the first engaging portion 322 of the cam 32. Then, the end 321 of the cam 32 is rotated to touch the protrusion 312 of the document feeder 30 along the spiral shape. Referring to FIG. 4, at last, the document feeder 30 is rotated to convey the document. The radius of the driven roller 20 is the same as the radius of the driven gear 33, so that they have the same angular velocity. The radius of the feed roller 50 is bigger than the radius of the pick-up roller 31, so that the tangent speed of the feed roller 50 is faster than the tangent speed of the pick-up roller 31.

When the pick-up roller 31 conveys the document to the feed roller 50, referring to FIG. 5, the document transfers a power from the feed roller 50 to rotate with the pick-up roller 31 so that the tangent speed of the pick-up roller 31 is changed as same as the tangent speed of the feed roller 50. At the same time, referring to FIG. 6, the speed of the pick-up roller 31 is faster than before, so that the protrusion 312 of the document feeder 30 pushes the cam 32 outwardly along the spiral shape 324. The end 321 of the cam 32 is untouched and separated from the shaft portion 311 so that the lump 331 of the driven gear 33 moves to and touches the second engaging portion 323 of the cam 32 along the inclined plane 325.

Moreover, as shown in FIG. 7, when the document leaves the pick-up roller 31, the pick-up roller 31 contacts another document and stops rotating because conveying power lost. However, the feed roller 50 continues rotating to convey the document. The driven roller 20 is still rotated such that the driven gear 33 is still rotated to drive the cam 32 to rotate. Referring to FIG. 3, then, the lump 331 touches the first engaging portion 322 of the cam 32. An intermittent time 200 which the cam 32 changes the state from the second engaging portion 323 to the first engaging portion 322 is defined. The pick-up roller 31 stops rotating during the intermittent time 200 resulting in separation of the document from a next feed-in document. Repeating the same process, and the document feeding apparatus 100 conveys the document one by one and prevents conveying two or more documents at the same time.

The present invention not only feeds the document, but also keeps separation of the feed-in document from a next feed-in document due to the pick-up roller 31 stopping rotating during the intermittent time 200.

It can be seen that the document feeding apparatus 100 has simple mechanism to achieve the object of the prevent invention. Further, the approach of the document feeding mechanism 100 is low cost.

Although a preferred embodiment of the present invention has been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will fall within the spirit and scope of the present invention, as defined in the appended claims. 

1. A document feeding apparatus comprising: a driven roller and a feed roller rotatable with a drive shaft; an idle roller gearing with the driven roller; and a document feeder including a pick-up roller having a shaft portion, a cam slipping into the shaft portion and a driven gear gearing with the idle roller, a protrusion disposed on the shaft portion, one end of the cam being a spiral shape defining an end thereof, and the other end being a hollow shape defining a first engaging portion and a second engaging portion thereof.
 2. The document feeding apparatus as claimed in claim 1, wherein a plane is disposed between the first engaging portion and the second engaging portion.
 3. The document feeding apparatus as claimed in claim 2, wherein the plane stretches from the first engaging portion to the second portion for forming an inclined plane.
 4. The document feeding apparatus as claimed in claim 1, further comprising a driving device, providing a power to drive the driven roller to rotate. 